A Dual-Boost H-Bridge Inverter With Common Ground for Photovoltaic Interfacing

Abstract

Microinverters for photovoltaic (PV) energy conversion typically encounter challenges, including the requirement of a voltage boost and suppression of the high-frequency leakage current. These challenges are usually not met simultaneously if only a standard full ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> )-bridge is used. Such limitation is, however, not applicable to the proposed dual-boost <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -bridge inverter, which uses only four switches and a unique dual-boost circuit for voltage boosting and forming a common ground. The latter stops PV terminal voltages from changing rapidly, and hence, no high-frequency capacitive current leaking to the ground even without using extra switches. Additionally, the proposed inverter can operate with either one or two PV sources whose terminal voltages need not be balanced. One of the source voltages can, in fact, fall to zero (due to shading) without affecting the continuous operation of the inverter, whose modulation has been formulated to keep its conduction losses low at a steady dc-link voltage. The dc-link capacitor across the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -bridge meanwhile decouples the pulsating output power, which in practice, has always challenged the design of single-phase microinverters. These intended performances have eventually been proven by the simulation and experimental results of a 500-W prototype.